After the claim of the projections of the climate models being “really conservative”, the scene continued with a conversation about the Greenland ice loss:
If climate stays at the temperature that it has been in in the last decade, Greenland is going away.
That is interesting. When I heard this claim, it started to itch to explore this a bit more. But before doing that, let’s see how the conversation on the glacier continued. Leonardo walks towards a crevasse in which there was a violent stream of glacial water finding its way to the ocean:
Don’t walk into the crevasse.
Oh, My God!
Don’t go too close to the edge.
Look how violent that is. Those rapids are going so incredibly fast.
This melt water is making its way to the sea. If that is not balanced by snowfall, then the ice sheet is getting smaller and sea level rises.
That is of course true, but. again, this made me wonder whether it is balanced by snowfall or not and if not, what is the difference?
Then they went to their “climate station” and Leonardo DiCaprio then noticed a 30 feet hose attached to the climate station:
This is actually our proper climate station.
This is a climate station? I was imagining a massive igloo with all kinds of scientists doing experiments. It really does look like broken down pool equipment.
Where does this connect to?
This is all melted out. Now this was a hose that went down 30 feet, now it melted out.
This that is lying here used to be straight down under ice? That is the amount of ice that has melted?
Leonardo DiCaprio took the hose and went to the helicopter to show the length (see screenshot).
That is the amount of ice that has melted?
This is five years of melt.
So this entire length is the thickness of ice that has melted throughout all lower Greenland in the past five years?
Right. That’s hundreds of cubic kilometres of ice that is no longer stored on land, it is gone into the sea over here.
That sentence was repeated many times in this scene. They sure wanted to hammer that down. Although I agree that, from a human standpoint, 30 foot (9 meter) seems a lot for a five year melt, my question would be how representative this area is for the melt in Greenland?
Questions, so many questions.
It was difficult to find exact numbers about the melt. Initially it was confusing. Some sources claimed an ice loss (mostly presented in mm sea level rise), but others claimed a gain.
Then I found this on the Danish Meteorological Institute (DMI) website (my emphasis):
Over the year, it snows more than it melts, but calving of icebergs also adds to the total mass budget of the ice sheet. Satellite observations over the last decade show that the ice sheet is not in balance. The calving loss is greater than the gain from surface mass balance, and Greenland is losing mass at about 200 Gt/yr.
Aha, that is probably the reason why some claim that it was shrinking while other said it was growing! More important, now I had a number that I could work with. The balance seem to be about 200 gigatons per year, which could confirm the rather ambiguous “hundreds of cubic kilometres”-claim (if we take the weight/volume conversion of water).
Those satellite observations over the last decade came probably from the GRACE satellites which were launched in 2002. I found somewhat more information about historical measurement from those satellites on the NASA website (my emphasis):
Research based on observations from NASA’s twin Gravity Recovery and Climate Experiment (GRACE) satellites indicates that between 2003 and 2013, Greenland shed approximately 280 gigatons of ice per year, causing global sea level to rise by 0.8 millimeters per year.
That seems to be all in the same ballpark.
Although 200 gigatons is a huge amount, Greenland is a big place. According to Wikipedia the total Greenland ice sheet volume is about 2,850,000 km3.
There was still the problem that the numbers are in different units. The melt was in gigatons, but the ice sheet volume is in cubic kilometers. Until now I equated 1 km3 with 1 gigaton (water). We are however talking about ice which is also water, but it expands when freezing. So it probably will be lighter for the same volume. Apparently, 1 m3 of ice seems to weigh 992 kg, so 1 km3 of ice weighs 0.992 gigaton. Indeed, still very close to that of water and it will not make any difference in the further calculations.
With all that information I could make some back-of-the-envelope calculations. This 200 gigatons of melted ice would make a whopping 0.007% of the total volume of the ice sheets of Greenland. If the ice would melt at the same rate, it will take many millenia for it to disappear (in the assumption we can keep emitting for so long).
That leaves me with the last question: how representative is the area where DiCaprio had his shock and awe moment. According to Wikipedia, the total surface of the Greenland ice sheet is 1,710,000 km2. If we calculate the volume of the melted ice in that area (the length of the hose which was 9 meter) over 5 years, the resulting melt is more than 15 times 200 gigatons. If it were representative, then it would be “thousands of cubic kilometers” in stead of the current “hundreds of cubic kilometers”. The melt of that part of Greenland seems not exactly representative for the total melt.
At the start of the scene, the name “Kangerlussuaq” appeared on the screen. So I did a search for that name and found information about the 2016 Greenland melt season, in which Kangerlussuaq (“Kangerdlugssuaq” in old Greenlandic spelling) is mentioned several times (my emphasis):
“Greater than average melt was observed in western and northeastern Greenland, as was also seen in 2015. A few areas along the eastern and southeastern coast near Helheim and Kangerdlugssuaq glaciers, saw frequent melting in 2016, resulting in increased ice exposure. Dark ice, typical along the central western Greenland coast, also appeared near Helheim and Kangerdlugssuaq glaciers.”
It is mentioned twice in a rather short summary, so it is most probably extraordinary. More interesting was the part about the “dark ice” and how it “appeared” near the Kangerlussuaq glaciers. Could that be a reason why this region is not representative? And what is the reason for the existence of that dark ice that is “typical along the central western Greenland coast”? And how does it “appear”?
Looking for more info, it seems that this “dark ice” is the subject of Jason Box’s research. Then I found this article about dark ice in Greenland in which he and his colleague Johnny Ryan were interviewed (my emphasis):
Ryan and Box discovered that the exposed dark ice appears so dark because it’s full of impurities. The ice is mixed with dust, algae and soot from wildfires that blazed thousands of years ago.
“So what happened in the past is having a direct effect on how the ice sheet behaves today,” Ryan said in a statement.
If it is true that the dark ice of Greenland is coming from historical wildfires, then this sheds a different light on the issue. We didn’t hear anything of that kind in this scene. Only pristine white ice was portrayed in it and not a peep about dark ice, let alone the origin of that dark ice.
To conclude this (already long) post: they not only failed to give the actual rate at which Greenland is losing ice, they also framed the melt much worse than it is by using an area that is not representative for the melt in Greenland. Not exactly an honest representation of the facts.
But then, how could I ever think that this documentary would be about the facts?